cupyx.scipy.signal.buttord#

cupyx.scipy.signal.buttord(wp, ws, gpass, gstop, analog=False, fs=None)[source]#

Butterworth filter order selection.

Return the order of the lowest order digital or analog Butterworth filter that loses no more than gpass dB in the passband and has at least gstop dB attenuation in the stopband.

Parameters:

wp (float) –
Passband and stopband edge frequencies.

For digital filters, these are in the same units as fs. By default, fs is 2 half-cycles/sample, so these are normalized from 0 to 1, where 1 is the Nyquist frequency. (wp and ws are thus in half-cycles / sample.) For example:
- Lowpass: wp = 0.2, ws = 0.3
- Highpass: wp = 0.3, ws = 0.2
- Bandpass: wp = [0.2, 0.5], ws = [0.1, 0.6]
- Bandstop: wp = [0.1, 0.6], ws = [0.2, 0.5]
For analog filters, wp and ws are angular frequencies (e.g., rad/s).
ws (float) –
Passband and stopband edge frequencies.

For digital filters, these are in the same units as fs. By default, fs is 2 half-cycles/sample, so these are normalized from 0 to 1, where 1 is the Nyquist frequency. (wp and ws are thus in half-cycles / sample.) For example:
- Lowpass: wp = 0.2, ws = 0.3
- Highpass: wp = 0.3, ws = 0.2
- Bandpass: wp = [0.2, 0.5], ws = [0.1, 0.6]
- Bandstop: wp = [0.1, 0.6], ws = [0.2, 0.5]
For analog filters, wp and ws are angular frequencies (e.g., rad/s).
gpass (float) – The maximum loss in the passband (dB).
gstop (float) – The minimum attenuation in the stopband (dB).
analog (bool, optional) – When True, return an analog filter, otherwise a digital filter is returned.
fs (float, optional) –
The sampling frequency of the digital system.

New in version 1.2.0.

Returns:

ord (int) – The lowest order for a Butterworth filter which meets specs.
wn (ndarray or float) – The Butterworth natural frequency (i.e. the “3dB frequency”). Should be used with butter to give filter results. If fs is specified, this is in the same units, and fs must also be passed to butter.